There's no obvious reason it shouldn't. The only question is which serial port XMODEM is designed to run with. Other communication programs I've found seem to have plugins for different hardware, so you'd just need to set up the system for the 2SIO cards used in the Altair.

no AT command necessary I don't think

Yes, it's necessary... you just don't see it because XMODEM hid that part of the communication. All smart modems have some sort of command interpreter, and even dumb modems still need a way to dial a phone number - my old Commodore modem, for example, used the programmable lines on the User port to trigger different oscillators to send DTMF tones, and the "pulse dialing" mode was even more primitive - the system literally just toggled the "off hook" line repeatedly to dial.

But in the case of terminal servers (that's what a "wifi modem" really is), you must send a string to the terminal server's controller to tell it to connect to a remote host. While most of these devices have adopted the AT standard, some people making homebrew devices may be using something like NodeMCU or MicroPython, which expect Lua or Python scripts.

(In fact, I'm building a terminal server using NodeMCU, just to be different. I haven't done anything with it lately... I really should get back to it and finish that project.)